Is 450 ppm (or less) politically possible? Midcourse correction

Because this series has turned out to be so popular, I’m going to expand it to cover more issues relevant to The Question of the Century Millenium in the headline. This post will lay out the full series as I now envision it, and the final post, probably sometime next week, will include a revised version of “The Solution,” the 14 wedges, based on recent input I have received

I am definitely open to being lobbied on the final 14 wedges. But only by people who take the trouble to go back to the original Princeton analysis (and my comments on it) and present seriously-calculated wedges that save 1 gigaton of carbon by 2050 and that don’t double count (i.e. don’t save carbon already saved by existing wedges).

That said, don’t waste your time trying to convince me there is more than one wedge of biofuels, nuclear, or coal with CCS. Too many smart people I know think those choices are already way too optimistic. [BTW, I would NOT use much of the biofuels wedge for car and light truck travel. I would use it for things like air travel and long-distance trucking.]

Here is how the series will unfold:

  1. Part 0, “The alternative is humanity’s self-destruction” [just posted], explains why failing to try to stabilize at 450 ppm is not a rational or moral choice.
  2. Part 1 (here) explained what Princeton’s stabilization wedges are, and why we probably need around 14 [four-decade] wedges, rather than 7 [five-decade wedges] to stabilize at 450 ppm.
  3. Part 2, “The Solution” explained what I believe the most plausible wedges are. This proved to be a very popular post, and the comments are well worth reading.
  4. Part 2.5, “The fuzzy math of the stabilization wedges,” explained why, yes, 14 or so wedges is in fact the right ballpark figure — even given the recent unusual coal-driven acceleration in global carbon dioxide emissions — because of a little-known assumption that Princeton made [This entry can be skipped by all non-wonks.]
  5. Part 2.6, “What is the impact of peak oil and peak coal?” explored how the world probably doesn’t have enough coal to sustain the recent CO2 trend for four decades or enough conventional oil to sustain even more historical growth trends for the next two decades.
  6. Part 3 will explain why some sort of massive government Apollo program or Manhattan project to develop new breakthrough technologies is not a priority component of the 450 ppm effort.
  7. Part 4 will explain what we should do about coal now, since we probably can’t afford to wait for a big price signal.
  8. Part 5 will explain how the increasingly painful reality of peak oil and climate change over the next two decades will create a “Midcourse correction” in national and global markets, mindset, and behavior, which will have a large, perhaps decisive, impact on the 450 ppm effort.
  9. Part 6 will look at what policies and carbon price are needed to get the 14 wedges and what role politics will play.
  10. Part 7 will take a final look at the solution, the 14 wedges, since it is already clear to me they need to be modified a bit [for instance, one of Princeton’s wedges is in fact not a wedge at all]. This post will also include links to the other posts, so it can serve as an entry point or one-stop link on this subject.

8 Responses to Is 450 ppm (or less) politically possible? Midcourse correction

  1. Norm Mosher says:


    Thanks for these posts. I am a TCP climate change presenter (sorry I missed you at Lise Vansusteren’s house last year) , and I am folding your stuff into my presentation. I am hoping you will consolidate the posts so we can access the whole easily.

    Thanks, again,

    Norm Mosher

  2. Ashley says:

    Yes! Thanks for consolidating! That will make reading it MUCH easier!

  3. It’s never a good idea to close your mind a priori to new data. You say that too many smart people have already told you that you’re too optimistic on nuclear. How much do they know about thorium and fluoride reactors? Have they researched what was done at ORNL in the 50s and 60s? Do they appreciate how different fluoride reactors can be than today’s light-water reactors?

    Keep your mind open to new information, then make your judgments, which should always be tentative and ready to accommodate innovation and improvement.

  4. Jared Gellert says:


    You have one wedge for cars at 60mpg, and then just below that you say most cars are electric or plug in hybrid. I’m somewhat confused about this, because if most cars are electric or can go at least 40 miles on zero carbon electricity, won’t cars average a whole lot more than 60mpg? If I analyse my families driving, and we live in suburbia, drive our kids to school every day etc, we’d get a lot more than 60 mpg with a plug-in hybrid, or an electric car with a 100 mile range. We’d almost never have to use petroleum.

    I also think that if applied engineering skill to greater gas mileage as opposed to acceleration, did something about reducing weight in cars, increased battery quality etc, all of these would make a substantial difference.

    I know this isn’t very technical and doesn’t have a lot of numbers, but its my effort to ask you to consider electrication of vehicles as possibly more than 1 wedge.

  5. Peter Wood says:

    Joe, I believe I have a wedge for you.

    The wedge is “reducing emissions from the consumption of greenhouse intensive commodities”. This would be from both reducing consumption of these commodities (possibly substituting less greenhouse intensive commodities), and using technologies that reduce emissions associated with their production (e.g. aluminium recycling).

    I believe I have a wedge because just three commodities: beef, aluminium, and cement, use over a GtC for their production. I am not including the land use change associated with beef production (land use change emissions from livestock are approx. 2.4 billion tons of CO2), because that could possibly be included in another wedge: “Reduced deforestation, plus reforestation, afforestation, and new plantations.” (Wedge 14, Pacala and Socolow, 2004).

    I am assuming that one wedge is a billion metric tonnes of carbon, which is 3.66 Gt CO2-e. I am also using 100 year IPCC AR4 global warming potentials for methane and N2O. I estimate that cement is presently responsible for 1.0 Gt CO2, aluminium is responsible for 471 Mt CO2, enteric emissions from beef are 65.8 Mt CH4 (1.646 Gt CO2-e), methane emissions from cattle manure are 7.49 Mt (187 Mt CO2-e), N2O emissions from cattle manure are 2.05 Mt (611 Mt CO2-e). These add up to 3.915 Gt CO2-e, slightly more than one wedge.

    There are other commodities that I have not included, such as other meats such as lamb, newsprint, steel, fertilisers, sugar, chemicals, and so on. The emissions from aluminium production are mainly from electricity so there could be a small amount of overlap with wedges that decarbonise electricity generation, but other commodities such as lamb and steel have significant emissions that are not electricity related. A policy that would suffice to drive emissions down by one wedge by 2050 would be a sufficiently high carbon price that covers emissions from as many sectors as possible.

    The figures for emissions from beef are from the FAO “Livestock’s Long Shadow” report:; I estimated the emissions from aluminium production by using aluminium production figures from, and an emissions intensity figure of 17.01 t CO2-e/t from; the cement production figure was obtained from ‘Emissions in the Platinum Age: the implications of rapid development for climate change mitigation’ by Ross Garnaut, Stephen Howes, Frank Jotzo and Peter Sheehan at



  6. jorma lehmijoki says:

    Potential energy of Greenland and The Antarctic ice.

    I calculate energy for whole the world for a century (10 million TWh) from Greenland generators as electricity and tenfold of the Antarctic icemass.

    And fresh water for all cities and dry areas. Forget all other energy making, that is enough.

  7. jorma lehmijoki says:

    And more of this. One cubic kilometer ice down 2500 meters makes 4 TWh, if you take an upper slice of 100 – 300 meters in Greenland for example.

    There is 3 million cubic kilometers ice in Greenland, and 500 000 km3 of it above the level 2500 m. First the upper level, and later the second best 2200 m and so on. You leave, of course, the downmost 500 meters there for albedo.

    The Greenland ice is melting away in any case, why let it melt into the sea and rise the sea level 7 meters? Makes no sense. Take the world-saving energy and ship the ice for water, no more climate catastrophe.

    Our new high voltage direct current cables have only 3% loss per 1000 km, so the cables connect USA, EU and China neatly in this electric grid.

    And hydrogen economy, that is there. Make hydrogen in Greenland (read The Antarctica), or in the far end of the cables where ever.

    This is the real wedge, and I am very surprised about the cleverness of our
    scientists when missing this simple solution for energy.